Plasma display device and method for driving plasma display device

ABSTRACT

A plasma display device has a plasma display panel, a scan electrode driving circuit, a sustain electrode driving circuit, and a data electrode driving circuit. In the sustain period of at least one subfield, the scan electrode driving circuit and the sustain electrode driving circuit apply a plurality of sustain pulses alternately to scan electrodes and sustain electrodes, and the data electrode driving circuit applies a data pulse to data electrodes by changing the timing according to the sustain pulses while the sustain pulses are applied.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCTINTERNATIONAL APPLICATION PCT/JP2009/002666.

TECHNICAL FIELD

The present invention relates to a driving method for a plasma displaypanel for use in a wall-mounted television or a large monitor, and to aplasma display device.

BACKGROUND ART

A typical AC surface discharge panel used as a plasma display panel(hereinafter simply referred to as “panel”) has a large number ofdischarge cells that are formed between a front plate and a rear platefacing each other. The front plate has the following elements:

-   -   a plurality of display electrode pairs, each formed of a scan        electrode and a sustain electrode, disposed on a front glass        substrate parallel to each other; and    -   a dielectric layer and a protective layer formed to cover the        display electrode pairs. The rear plate has the following        elements:    -   a plurality of parallel data electrodes formed on a rear glass        substrate;    -   a dielectric layer formed over the data electrodes so as to        cover the electrodes;    -   a plurality of barrier ribs formed on the dielectric layer        parallel to the data electrodes; and    -   phosphor layers formed on the surface of the dielectric layer        and on the side faces of the barrier ribs. The front plate and        the rear plate face each other so that the display electrode        pairs and the data electrodes three-dimensionally intersect, and        are sealed together. A discharge gas containing xenon in a        partial pressure ratio of 10%, for example, is sealed into the        inside discharge space. Discharge cells are formed in portions        where the display electrode pairs face the data electrodes. In a        panel having such a structure, gas discharge generates        ultraviolet light in each discharge cell. This ultraviolet light        excites the red, green, and blue phosphors so that the phosphors        emit the corresponding colors for color display.

A subfield method is typically used as a method for driving the panel.In the subfield method, one field period is divided into a plurality ofsubfields, and combination of subfields of light emission providesgradation display. Each subfield has an initializing period, an addressperiod, and a sustain period. In the initializing period, aninitializing discharge is caused in each discharge cell to form wallcharge necessary for the subsequent address operation on each electrode.In the address period, address discharge is caused to form wall chargeselectively in the discharge cells to be lit. In the sustain period,sustain pulses are applied alternately to the display electrode pairs,each formed of a scan electrode and a sustain electrode. Thereby, asustain discharge is caused in the discharge cells having undergone theaddress discharge to cause the phosphor layers of the correspondingdischarge cells to emit light. In this manner, an image is displayed.

As a circuit for applying sustain pulses to the display electrode pairs,a so-called power recovery circuit capable of reducing power consumptionis typically used (see Patent Literature 1, for example). In PatentLiterature 1, focusing on the fact that each display electrode pair is acapacitive load having interelectrode capacitance between the displayelectrode pair, the inventors have disclosed a power recovery circuit.Using a resonance circuit including an inductor as a component thereof,the power recovery circuit causes LC resonance between the inductor andthe interelectrode capacitance. Then, the power recovery circuitrecovers the electric charge stored in the interelectrode capacitanceand reuses the recovered charge to drive the display electrode pairs.

Meanwhile, with recent increases in the screen size and definition,various efforts are made to improve the emission efficiency andluminance of the panel. For example, studies are actively made forconsiderably enhancing the emission efficiency by increasing the xenonpartial pressure. However, increasing the xenon partial pressureincreases variations in the discharge timing, thus causing variations inthe emission intensity in each discharge cell. This phenomenon can makedisplay luminance non-uniform in some cases. In order to improve thisnon-uniform luminance, a driving method is disclosed (see PatentLiterature 2, for example). This driving method makes the displayluminance uniform by inserting a sustain pulse having a steep risingedge at a rate of once every plurality of times, for example, andmatching the sustain discharge timings.

When, at an increased xenon partial pressure, a high-luminance image isdisplayed after a still image has been displayed for an extended periodof time, the still image is recognized as an afterimage and the imagedisplay quality is degraded in some cases. In order to reduce such aphenomenon of persistence of vision, a method is disclosed (see PatentLiterature 3, for example). This method suppresses degradation of imagedisplay quality by moving the display position of an image likely tocause an afterimage.

However, in the method disclosed in Patent Literature 3, although therecognition of an afterimage can be reduced, insertion of a sustainpulse having a steep rising edge increases the reactive power of thedriving circuit and power consumption. Further, the movement of electriccharge between adjacent cells becomes active at the rising timing of thesteep pulse in the sustain period. This phenomenon easily causes afailure in display, i.e. false lighting of the cells to be unlit.

Citation List Patent Literature]

[PTL1] Japanese Patent Examined Publication No. H07-109542

[PTL2] Japanese Patent Unexamined Publication No. 2005-338120

[PTL3] Japanese Patent Unexamined Publication No. H08-248934

SUMMARY OF INVENTION

A plasma display device has the following elements:

-   -   a plasma display panel including:        -   a first substrate having display electrode pairs in a            parallel direction, each of the display electrode pairs            being formed of a scan electrode and a sustain electrode;            and        -   a second substrate having data electrodes in a vertical            direction,        -   the first substrate and the second substrate being disposed            so that discharge cells are formed in intersecting parts of            the display electrode pairs and the data electrodes;    -   a scan electrode driving circuit for driving the scan        electrodes;    -   a sustain electrode driving circuit for driving the sustain        electrodes; and    -   a data electrode driving circuit for driving the data        electrodes,    -   the plasma display panel being driven by a subfield method where        one field is formed of a plurality of subfields.        In the sustain period of at least one of the subfields, the scan        electrode driving circuit and the sustain electrode driving        circuit apply a plurality of sustain pulses alternately to the        scan electrodes and the sustain electrodes, and the data        electrode driving circuit applies a data pulse to the data        electrodes by changing the timing according to the sustain        pulses while the sustain pulses are applied.

This operation can provide high-fidelity image display, reduce aphenomenon of persistence of vision itself, and suppress the powerconsumption necessary for light emission of the panel.

The data electrode driving circuit applies the data pulse to the dataelectrodes at the timing such that the light emission of a firstdischarge is stronger than the light emission of a second discharge.Alternatively, the data electrode driving circuit may apply the datapulse to the data electrodes at the timing such that the light emissionof the second discharge is stronger than the light emission of the firstdischarge.

In the plasma display device of the present invention, the timings atwhich the data electrode driving circuit applies the data pulse to thedata electrodes may be a first predetermined timing and a secondpredetermined timing.

In the plasma display device of the present invention, the timing atwhich the data electrode driving circuit applies the data pulse to thedata electrodes may be before or after the timing at which the sustainpulses applied to the scan electrodes or the sustain electrodes areclamped to a predetermined voltage.

In a driving method for a plasma display device, the plasma displaydevice has the following elements:

-   -   a plasma display panel including:        -   a first substrate having display electrode pairs, each            formed of a scan electrode and a sustain electrode, in a            parallel direction; and        -   a second substrate having data electrodes in a vertical            direction,        -   the first substrate and the second substrate being disposed            so that discharge cells are formed in intersecting parts of            the display electrode pairs and the data electrodes;    -   a scan electrode driving circuit for driving the scan        electrodes;    -   a sustain electrode driving circuit for driving the sustain        electrodes; and    -   a data electrode driving circuit for driving the data        electrodes,    -   the plasma display panel being driven by a subfield method where        one field is formed of a plurality of subfields.        In the sustain period of at least one of the subfields, the scan        electrode driving circuit and the sustain electrode driving        circuit apply sustain pulses alternately to the scan electrodes        and the sustain electrodes, and the data electrode driving        circuit applies a data pulse to the data electrodes by changing        the timing while the sustain pulses are applied.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view showing a structure of a panel ina plasma display device in accordance with an exemplary embodiment ofthe present invention.

FIG. 2 is an electrode array diagram of the panel.

FIG. 3 is a waveform chart of driving voltages applied to the respectiveelectrodes of the panel.

FIG. 4 is a circuit block diagram of the plasma display device inaccordance with the exemplary embodiment.

FIG. 5 is a waveform chart of driving voltages applied in a sustainperiod in the plasma display device in accordance with the exemplaryembodiment.

FIG. 6 is a diagram showing an example of waveforms of a sustain pulseand a data pulse applied in the sustain period in the plasma displaydevice in accordance with the exemplary embodiment.

FIG. 7 is a diagram showing another example of waveforms of a sustainpulse and a data pulse applied in the sustain period in the plasmadisplay device in accordance with the exemplary embodiment.

FIG. 8 is a diagram showing still another example of waveforms of asustain pulse and a data pulse applied in the sustain period in theplasma display device in accordance with the exemplary embodiment.

FIG. 9 is a driving waveform chart showing an example of an arrangementof sustain pulses in the sustain period in the plasma display device inaccordance with the exemplary embodiment.

FIG. 10 is a driving waveform chart showing another example of anarrangement of sustain pulses in the sustain period in the plasmadisplay device in accordance with the exemplary embodiment.

FIG. 11 is a circuit diagram of sustain pulse generating circuits in theplasma display device in accordance with the exemplary embodiment.

FIG. 12 is a diagram showing a circuit configuration of a data electrodedriving circuit in the plasma display device in accordance with theexemplary embodiment.

DESCRIPTION OF EMBODIMENTS First Exemplary Embodiment

FIG. 1 is an exploded perspective view showing a structure of panel 10in a plasma display device in accordance with the exemplary embodimentof the present invention. A plurality of display electrode pairs 24,each formed of scan electrode 22 and sustain electrode 23, are formed onglass front plate 21, i.e. a first substrate, in the horizontaldirection of panel 10. Dielectric layer 25 is formed so as to coverdisplay electrode pairs 24. Protective layer 26 is formed overdielectric layer 25. A plurality of data electrodes 32 are formed onrear plate 31, i.e. a second substrate, in the vertical direction ofpanel 10. Dielectric layer 33 is formed so as to cover data electrodes32, and mesh barrier ribs 34 are formed on data electrodes 32. On theside faces of barrier ribs 34 and on the surface of dielectric layer 33,phosphor layers 35 each emitting red, green, or blue light are formed.

Front plate 21 and rear plate 31 face each other so that displayelectrode pairs 24 intersect with data electrodes 32 with a smalldischarge space sandwiched between the electrodes. The outer peripheriesof these front plate 21 and rear plate 31 are sealed with a sealingmaterial, e.g. a glass frit. A mixed gas of neon and xenon, for example,is sealed into the discharge space as a discharge gas. The dischargespace is partitioned into a plurality of compartments by barrier ribs34. Discharge cells are formed in intersecting parts of displayelectrode pairs 24 and data electrodes 32. The discharge cells dischargeand emit light to display an image.

The structure of panel 10 is not limited to the above, and may includebarrier ribs formed in a stripe pattern, for example.

FIG. 2 is an electrode array diagram of panel 10 in accordance with theexemplary embodiment of the present invention. Panel 10 has n scanelectrode SC1 through scan electrode SCn (scan electrodes 22 in FIG. 1)and n sustain electrode SU1 through sustain electrode SUn (sustainelectrodes 23 in FIG. 1) both long in the row direction. Panel 10 alsohas m data electrode D1 through data electrode Dm (data electrodes 32 inFIG. 1) long in the column direction. A discharge cell is formed in thepart where a pair of scan electrode SCi (i being 1 through n) andsustain electrode SUi (i being 1 through n) intersects with one dataelectrode Dj (j being 1 through m). Thus m×n discharge cells are formedin the discharge space. Incidentally, as shown in FIG. 1 and FIG. 2,scan electrode SCi and sustain electrode SUi are formed in pairsparallel to each other. For this reason, interelectrode capacitance Cpexists between scan electrode SC1 through scan electrode SCn and sustainelectrode SU1 through sustain electrode SUn.

Next, driving voltage waveforms for driving panel 10 and the operationthereof are described.

A plasma display device displays gradations by a subfield method: onefield period is divided into a plurality of subfields, and lightemission and no light emission in each discharge cell are controlled ineach subfield. Each subfield (SF) has an initializing period, an addressperiod, and a sustain period. In the initializing period, aninitializing discharge is caused in each discharge cell to form wallcharge necessary for the subsequent address discharge on each electrode.In the address period, an address discharge is caused to form wallcharge selectively in the discharge cells to be lit. In the sustainperiod, a number of sustain pulses equal in number to the luminanceweight multiplied by the luminance magnification are applied alternatelyto display electrode pairs 24 to cause a sustain discharge in thedischarge cells having undergone the address discharge.

In the exemplary embodiment, one field is divided into ten subfields(the first SF, and second SF through tenth SF), and the respectivesubfields have luminance weights of 1, 2, 3, 6, 11, 18, 30, 44, 60, and80, for example. In the initializing period of the first SF, aninitializing operation is performed in all the discharge cells. In theinitializing periods of the second SF through the tenth SF, theinitializing operation is performed selectively in the discharge cellshaving undergone a sustain discharge. However, in the present invention,the number of subfields and the luminance weights of the respectivesubfields are not limited to the above values.

FIG. 3 is a waveform chart of driving voltages applied to the respectiveelectrodes of panel 10 in accordance with the exemplary embodiment ofthe present invention. FIG. 3 shows driving voltage waveforms in twosubfields. Because the driving voltage waveforms in other subfields aresubstantially similar, the description of those waveforms is omitted.

In the first half of the initializing period of the 1st SF, 0(V) isapplied to each of data electrode D1 through data electrode Dm andsustain electrode SU1 through sustain electrode SUn, and an up-rampwaveform voltage is applied to scan electrode SC1 through scan electrodeSCn. Here, the up-ramp waveform voltage gradually rises from voltageVi1, which is equal to or lower than a breakdown voltage, toward voltageVi2, which exceeds the breakdown voltage with respect to sustainelectrode SU1 through sustain electrode SUn. While this up-ramp voltageis rising, a weak initializing discharge occurs between scan electrodeSC1 through scan electrode SCn and sustain electrode SU1 through sustainelectrode SUn, and between scan electrode SC1 through scan electrode SCnand data electrode D1 through data electrode Dm. Then, negative wallvoltage accumulates on scan electrode SC1 through scan electrode SCn.Positive wall voltage accumulates on data electrode D1 through dataelectrode Dm and sustain electrode SU1 through sustain electrode SUn.Here, the wall voltage on the electrodes means the voltage generated bythe wall charge that are accumulated on dielectric layer 25 coveringelectrodes 22 and electrodes 23, dielectric layer 33 covering electrodes32, protective layer 26, phosphor layers 35, or the like.

In the second half of the initializing period, positive voltage Ve1 isapplied to sustain electrode SU1 through sustain electrode SUn, and adown-ramp waveform voltage is applied to scan electrode SC1 through scanelectrode SCn. Here, the down-ramp waveform voltage gradually falls fromvoltage Vi3, which is equal to or lower than the breakdown voltage,toward voltage Vi4, which exceeds the breakdown voltage with respect tosustain electrode SU1 through sustain electrode SUn. In thisapplication, a weak initializing discharge occurs between scan electrodeSC1 through scan electrode SCn and sustain electrode SU1 through sustainelectrode SUn, and between scan electrode SC1 through scan electrode SCnand data electrode D1 through data electrode Dm. This weak dischargereduces the negative wall voltage on scan electrode SC1 through scanelectrode SCn and the positive wall voltage on sustain electrode SU1through sustain electrode SUn, and adjusts the positive wall voltage ondata electrode D1 through data electrode Dm to a value appropriate forthe address operation. In this manner, the initializing operation iscompleted.

As the driving voltage waveforms in the initializing period, voltagewaveforms only in the second half of the initializing period, as shownin the initializing period of the 2nd SF in FIG. 3, may be applied. Inthis case, an initializing discharge occurs selectively in the dischargecells having undergone a sustain discharge in the sustain period of theimmediately preceding subfield.

In the subsequent address period, voltage Ve2 is applied to sustainelectrode SU1 through sustain electrode SUn, and voltage Vc is appliedto scan electrode SC1 through scan electrode SCn.

Next, negative scan pulse Va is applied to scan electrode SC1 in thefirst row, and positive address pulse Vd is applied to data electrode Dk(k being 1 through m) in a discharge cell to be lit in the first rowamong data electrode D1 through data electrode Dm. At this time, thevoltage difference in the intersecting part of data electrode Dk andscan electrode SC1 is obtained by adding the difference in an externallyapplied voltage (Vd−Va) and the difference between the wall voltage ondata electrode Dk and the wall voltage on scan electrode SC1, and thusexceeds the breakdown voltage. Then, an address discharge occurs betweendata electrode Dk and scan electrode SC1, and between sustain electrodeSU1 and scan electrode SC1. Positive wall voltage accumulates on scanelectrode SC1, and negative wall voltage accumulates on sustainelectrode SU1. Negative wall voltage also accumulates on data electrodeDk.

In this manner, the address operation is performed to cause the addressdischarge in the discharge cells to be lit in the first row and toaccumulate wall voltages on the corresponding electrodes. On the otherhand, the voltage in the intersecting parts of data electrode D1 throughdata electrode Dm applied with no address pulse Vd and scan electrodeSC1 does not exceed the breakdown voltage, and thus no address dischargeoccurs. The above address operation is repeated until the operationreaches scan electrode SCn in the discharge cells in the n-th row, andthe address period is completed.

In the subsequent sustain period, in the exemplary embodiment, a sustainpulse having a gradual rising edge is applied to each of scan electrodeSC1 through scan electrode SCn and sustain electrode SU1 through sustainelectrode SUn, so that a sustain discharge is caused in the dischargecells having undergone the address discharge. The sustain pulses will bedetailed later. First, the operation in the sustain period is outlined.

In the sustain period, first, a sustain pulse is applied to scanelectrode SC1 through scan electrode SCn, and 0(V) is applied to sustainelectrode SU1 through sustain electrode SUn. Then, in the dischargecells having undergone the address discharge, the voltage differencebetween scan electrode SCi and sustain electrode SUi is obtained byadding the difference between the wall voltage on scan electrode SCi andthe wall voltage on sustain electrode SUi to sustain pulse voltage Vs,and thus exceeds the breakdown voltage. Then, a sustain discharge occursbetween scan electrode SCi and sustain electrode SUi, and ultravioletlight generated at this time causes phosphor layers 35 to emit light.Negative wall voltage accumulates on scan electrode SCi, and positivewall voltage accumulates on sustain electrodes SUi. Positive wallvoltage also accumulates on data electrode Dk. In the discharge cellshaving undergone no address discharge in the address period, no sustaindischarge occurs and the wall voltage at the completion of theinitializing period is maintained.

Subsequently, 0 (V) is applied to scan electrode SC1 through scanelectrode SCn, and a sustain pulse is applied to sustain electrode SU1through sustain electrode SUn. Then, in the discharge cell havingundergone the sustain discharge, the voltage difference between sustainelectrode SUi and scan electrode SCi exceeds the breakdown voltage.Thereby, a sustain discharge occurs between sustain electrode SUi andscan electrode SCi again. Negative wall voltage accumulates on sustainelectrode SUi, and positive wall voltage accumulates on scan electrodeSCi.

Similarly, sustain pulses corresponding in number to the luminanceweight are applied alternately to scan electrode SC1 through scanelectrode SCn and sustain electrode SU1 through sustain electrode SUn tocause a potential difference between the electrodes of each displayelectrode pair. Thereby, the sustain discharge is continued in thedischarge cells having undergone the address discharge in the addressperiod.

At the end of the sustain period, a voltage difference in the shape of aso-called narrow pulse is caused between scan electrode SC1 through scanelectrode SCn and sustain electrode SU1 through sustain electrode SUn.Thereby, while a positive wall voltage is left on data electrode Dk, thewall voltages on scan electrode SCi and sustain electrode SUi areerased. In this manner, the sustain operation in the sustain period iscompleted.

The operation in the subsequent subfield is substantially similar to theoperation in the first SF, and thus the description thereof is omitted.

FIG. 5 is a waveform chart of driving voltages applied in a sustainperiod in plasma display device 1 in accordance with the exemplaryembodiment of the present invention. The feature of the driving methodfor panel 10 of the exemplary embodiment is to control the timing ofcausing sustain discharges by applying a data voltage to data electrodeDi in synchronism with a plurality of sustain pulses applied to scanelectrode SCi and sustain electrode SUi in the sustain period, as shownin FIG. 5. That is, driving the panel by applying a data voltage to dataelectrode Di every successive N (N being an integer equal to or largerthan 2) sustain pulses is repeated. The above driving cycle may includea driving state where no data voltage is applied to data electrode Di insynchronism with the plurality of sustain pulses. In the followingdescription, the relation between the sustain pulses and the datavoltage to be applied to data electrode Di in the exemplary embodimentis detailed.

FIG. 6 through FIG. 8 are waveforms for detailing three sustain pulsewaveforms used in the exemplary embodiment of the present invention. Ineach of these waveforms, the horizontal axis represents time. In eachchart, the middle waveform shows a voltage waveform (sustain pulse)applied to scan electrodes 22 or sustain electrodes 23 in the sustainperiod. The bottom waveform shows a voltage waveform (data pulse)applied to data electrodes 32 in the sustain period. The top waveformschematically shows the light emission state in the discharge cell whenboth of the middle and bottom voltage waveforms are applied. Thevertical axis in the top waveform represents emission intensity. Thatis, the portion projecting downwardly shows the magnitude of lightemission caused by a discharge. In the exemplary embodiment, thetemporal positions of two strong light emissions are shown. Hereinafter,according to the combination of the sustain pulse and the data pulse,the states in FIG. 6 through FIG. 8 are referred to as a first sustainpulse state, a second sustain pulse state, and a third sustain pulsestate for differentiation.

FIG. 6 is a diagram schematically showing the sustain pulse and datapulse and the state of light emission in the first sustain pulse state.As shown by the middle waveform, period T1, i.e. the rising time of thesustain pulse, is 650 nsec. Thereafter, during period T2, the sustainpulse is maintained at voltage Vs as a predetermined voltage. As shownby the bottom waveform, no data pulse is applied to data electrodes 32in the first sustain pulse state.

As shown by the top waveform, light emission is caused by a discharge inthe portions projecting downwardly. This diagram shows a state where twolight emissions are caused by strong discharges.

FIG. 7 is a diagram schematically showing the sustain pulse and datapulse and the state of light emission in the second sustain pulse state.Similarly to the first sustain pulse state, period T1, i.e. the risingtime of the sustain pulse in the second sustain pulse state, is 650nsec. Thereafter, during period T2, the sustain pulse is maintained atvoltage Vs as the predetermined voltage. However, this pulse state isdifferent from the first sustain pulse state in that, at time d1 550nsec after the rising timing of the sustain pulse, i.e. a firstpredetermined timing, a data pulse having a pulse width Tw1 (100 nsec)is applied to data electrodes 32. That is, as shown in FIG. 7, time d1,i.e. the first predetermined timing, is included in period T1, i.e. therising time of the sustain pulse.

Similarly to FIG. 6, also in FIG. 7, light emission is caused by adischarge in the portions projecting downwardly, as shown by the topwaveform.

FIG. 8 is a diagram schematically showing the sustain pulse and datapulse and the state of light emission in the third sustain pulse state.Similarly to the first sustain pulse state, period T1, i.e. the risingtime of the sustain pulse in the third sustain pulse state, is 650 nsec.Thereafter, during period T2, the sustain pulse is maintained at voltageVs as the predetermined voltage. However, this pulse state is differentfrom the first sustain pulse state in that, at time d2 750 nsec afterthe rising timing of the sustain pulse, i.e. a second predeterminedtiming, a data pulse having a pulse width Tw2 (100 nsec) is applied todata electrodes 32. That is, as shown in FIG. 8, time d2, i.e. thesecond predetermined timing, is included in period T2 during which thesustain pulse is maintained at voltage Vs as the predetermined voltage.

Similarly to FIG. 6, also in FIG. 8, light emission is caused by adischarge in the portions projecting downwardly, as shown by the topwaveform.

FIG. 9 is a driving waveform chart showing a temporal arrangement of thestates where voltages are applied to scan electrodes 22, sustainelectrodes 23, and data electrodes 32 in accordance with the exemplaryembodiment of the present invention. In this case, the electrodes aredriven in a manner such that the first sustain pulse state, the secondsustain pulse state, and the third sustain pulse state are arranged inthis order. One cycle period is formed of additional two successivefirst pulse states arranged after the third sustain pulse state. It isshown that scan electrodes 22, sustain electrodes 23, and dataelectrodes 32 are driven in such a cycle.

FIG. 10 is a driving waveform chart showing another example of atemporal arrangement of the states where voltages are applied to scanelectrodes 22, sustain electrodes 23, and data electrodes 32 inaccordance with another exemplary embodiment of the present invention.In this case, one cycle period is formed of the first sustain pulsestate, the second sustain pulse state, the second sustain pulse state,the first sustain pulse state, the first sustain pulse state, and thethird sustain pulse state arranged in this order. Scan electrodes 22,sustain electrodes 23, and data electrodes 32 are driven in such acycle.

As described above, plasma display device 1 of the exemplary embodimentcauses at least two discharges having different magnitudes in thedischarge cells by driving the electrodes in the sustain period of atleast one of the subfields in the following manner. Scan electrodedriving circuit 53 and sustain electrode driving circuit 54 apply aplurality of sustain pulses alternately to scan electrodes 22 andsustain electrodes 23, and data electrode driving circuit 52 applies adata pulse to data electrodes 32 by changing the timing according to thesustain pulses while the sustain pulses are applied.

Data electrode driving circuit 52 of the exemplary embodiment applies adata pulse to data electrodes 32 while sustain pulses are applied toscan electrodes 22 or sustain electrodes 23. In the sustain period, atleast two types of sustain pulse with application of data pulses atdifference timings, and a sustain pulse without application of datapulse may be arranged.

A phenomenon of persistence of vision is caused by a change in theemission intensity of a discharge cell depending on the history of thelight emission of the discharge cell. For example, an afterimage isrecognized in the following case: after a lit discharge cell and anunlit discharge cell have maintained the states for a certain period oftime by displaying a still image for an extended period time, forexample, the entire screen is lit. When the emission intensity of thelit discharge cell is higher than the emission intensity of the unlitdischarge cell, a positive afterimage occurs. In the opposite case, anegative afterimage occurs. Further, when the still image is displayedfor a longer time, such an afterimage tends to be stronger.

The inventors have experimentally verified that the phenomenon ofpersistence of vision can be reduced by controlling the arrangement ofthe combinations of sustain pulses and data pulses and the risingtimings of the data pulses, using the driving method for panel 10 of theexemplary embodiment. Then, the inventors have found that it ispreferable to set the positions of the sustain pulses and data pulsesoptimum depending on the occurrence of the positive or negativeafterimage and the strength thereof. Specifically, it is found that thephenomenon of persistence of vision itself is reduced and the displayluminance of the respective discharge cells can be made uniform bycausing sustain discharges in combination of the following three sustainpulse states: the first sustain pulse state where no data pulse isapplied to data electrodes 32; the second sustain pulse state where adischarge is caused at a timing earlier than the rising time of thesustain pulse; and the third sustain pulse state where a discharge iscaused at a timing later than the rising timing of the sustain pulse.

Further, according to the light-emitting rate of each subfield, thearrangement of sustain pulses of FIG. 9 and the arrangement of sustainpulses of FIG. 10 may be switched for driving the electrodes. Forexample, at a high light-emitting rate, a discharge tends to be causedlater than the rising timing of a sustain pulse. Thus the number ofsecond sustain pulse states can be increased in the arrangement to causethe discharge earlier. At a low light-emitting rate, the number of thirdsustain pulse states can be increased in the arrangement to cause thedischarge later.

Next, a description is provided for driving circuits for driving panel10 and the operation thereof. FIG. 4 is a circuit block diagram ofplasma display device 1 that includes panel 10 in accordance with theexemplary embodiment of the present invention. Plasma display device 1has panel 10, image signal processing circuit 51, data electrode drivingcircuit 52, scan electrode driving circuit 53, sustain electrode drivingcircuit 54, timing generating circuit 55, and power supply circuits (notshown) for supplying necessary power to each circuit block.

Image signal processing circuit 51 converts input image signal sig intoimage data showing light emission and no light emission in eachsubfield. Data electrode driving circuit 52 converts the image data ineach subfield into signals corresponding to each of data electrode D1through data electrode Dm, and drives each of data electrode D1 throughdata electrode Dm.

Timing generating circuit 55 generates various timing signals forcontrolling the operation of each circuit block according to horizontalsynchronizing signal H and vertical synchronizing signal V, and suppliesthe timing signals to each circuit block. Scan electrode driving circuit53 has sustain pulse generating circuit 100 for generating sustainpulses to be applied to scan electrode SC1 through scan electrode SCn insustain periods, and drives each of scan electrode SC1 through scanelectrode SCn according to the timing signals. Sustain electrode drivingcircuit 54 has sustain pulse generating circuit 200 for generatingsustain pulses to be applied to sustain electrode SU1 through sustainelectrode SUn in sustain periods, and drives sustain electrode SU1through sustain electrode SUn according to the timing signals.

Next, a description is provided for the details and operation of sustainpulse generating circuit 100 and sustain pulse generating circuit 200.FIG. 11 is a circuit diagram of sustain pulse generating circuit 100 andsustain pulse generating circuit 200 in accordance with the exemplaryembodiment of the present invention. In FIG. 11, the interelectrodecapacitance of panel 10 is shown as Cp, and the circuits for generatingscan pulses and initializing voltage waveforms are omitted.

Sustain pulse generating circuit 100 has power recovery circuit 110 andclamp circuit 120. Power recovery circuit 110 has power recoverycapacitor C10, switching element Q11, switching element Q12, blockingdiode D11, blocking diode D12, and resonance inductor L10. Clamp circuit120 has switching element Q13 for clamping scan electrodes 22 to powersupply VS having a voltage of Vs, and switching element Q14 for clampingscan electrodes 22 to the ground potential. Power recovery circuit 110and clamp circuit 120 are coupled to scan electrodes 22, i.e. one end ofinterelectrode capacitance Cp of panel 10, through a scan pulsegenerating circuit (not shown because the circuit is short-circuited inthe sustain periods).

Power recovery circuit 110 causes LC resonance between interelectrodecapacitance Cp and inductor L10 to make a sustain pulse rise and fall.In the rising time of a sustain pulse, the electric charge stored inpower recovery capacitor C10 is moved to interelectrode capacitance Cpthrough switching element Q11, diode D11, and inductor L10. In thefalling time of the sustain pulse, the electric charge stored ininterelectrode capacitance Cp of panel 10 is returned to power recoverycapacitor C10 through inductor L10, diode D12, and switching elementQ12. In this manner, sustain pulses are applied to scan electrodes 22.

Power recovery circuit 110 thus drives scan electrodes 22, using LCresonance, and thereby reduces power consumption. Power recoverycapacitor C10 has a capacitance sufficiently larger than interelectrodecapacitance Cp, works as a power supply of power recovery circuit 110,and is charged to approximately Vs/2, i.e. a half of voltage Vs of powersupply VS.

Clamp circuit 120 allows scan electrodes 22 to be coupled to powersupply VS through switching element Q13 and clamped to voltage Vs.Further, the clamp circuit allows scan electrodes 22 to be groundedthrough switching element Q14 and clamped to 0 (V). Clamp circuit 120thus drives scan electrodes 22. For this reason, the impedance duringvoltage application of clamp circuit 120 is small and thus a largedischarge current can be supplied by a strong sustain discharge in astable manner.

In this manner, in sustain pulse generating circuit 100, switchingelement Q11, switching element Q12, switching element Q13, and switchingelement Q14 are controlled so that sustain pulses are applied t o scanelectrodes 22 using power recovery circuit 110 and clamp circuit 120.These switching elements can be formed of generally known devices, suchas a metal-oxide-semiconductor field-effect transistor (MOSFET) and aninsulated gate bipolar transistor (IGBT).

Sustain pulse generating circuit 200 has power recovery circuit 210 andclamp circuit 220. The power recovery circuit has power recoverycapacitor C20, switching element Q21, switching element Q22, blockingdiode D21, blocking diode D22, and resonance inductor L20. The clampcircuit has switching element Q23 for clamping sustain electrodes 23 tovoltage Vs, and switching element Q24 for clamping sustain electrodes 23to the ground potential. The sustain pulse generating circuit is coupledto sustain electrodes 23, i.e. one end of interelectrode capacitance Cpof panel 10. The operation of sustain pulse generating circuit 200 issimilar to that of sustain pulse generating circuit 100, and thedescription thereof is omitted. The period of LC resonance betweeninductor L10 of power recovery circuit 110 and interelectrodecapacitance Cp of panel 10, and the period of LC resonance (hereinafterreferred to as “resonance period”) between inductor L20 of powerrecovery circuit 210 and interelectrode capacitance Cp of the panel canbe obtained by the formula “2π√{square root over ( )}(LCp)” where theinductance of each of inductor L10 and inductor L20 is L. In theexemplary embodiment, inductor L10 and inductor L20 are set so that theresonance periods in power recovery circuit 110 and power recoverycircuit 210 are each approximately 1,600 nsec.

Next, the data electrode driving circuit is described. FIG. 12 is acircuit diagram showing an example of a configuration of data electrodedriving circuit 52 of FIG. 4.

Data electrode driving circuit 52 of FIG. 12 has a plurality ofp-channel FETs (each being a field-effect transistor, hereinafter simplyreferred to as a transistor) Q211 through Q21 m, and a plurality ofn-channel FETs (each being a field-effect transistor, hereinafter simplyreferred to as a transistor) Q221 through Q22 m. Power supply terminalV201 is connected to node N201. Voltage Vd is applied to power supplyterminal V201.

Transistor Q211 through transistor Q21 m are connected between node N201and node ND1 through node NDm, respectively. Transistor Q221 throughtransistor Q22 m are connected between node ND1 through NDm and theground terminals. Node ND1 through node NDm are connected tocorresponding data electrode D1 through data electrode Dm of FIG. 2.

Control signal S201 through control signal S20 m are input to the gatesof the plurality of transistor Q211 through transistor Q21 m,respectively. Control signal S201 through control signal S20 m are alsoinput to the gates of transistor Q221 through transistor Q22 m,respectively. The above control signal S201 through control signal S20 mare input, as timing signals, to data electrode driving circuit 52 fromtiming generating circuit 55 of FIG. 4.

Next, the operation of the sustain pulse generating circuit and the datapulse generating circuit is described with reference to FIG. 6 throughFIG. 8. Herein, the description is provided for sustain pulse generatingcircuit 100 on the side of scan electrodes 22. Sustain pulse generatingcircuit 200 on the side of sustain electrodes 23 has a similar circuitstructure and performs substantially similar operation.

First, the first sustain pulse state of FIG. 6 is described.

(Period T1)

In order to generate a sustain pulse in period T1, i.e. the rising timeof the sustain pulse, switching element Q11 is turned on at time t1.Then, electric charge starts to move from power recovery capacitor C10to scan electrodes 22 through switching element Q11, diode D11, andinductor L10, so that the voltage of scan electrodes 22 starts to rise.Then, in the discharge cells having undergone an address discharge inthe address period, the voltage difference between scan electrodes 22and sustain electrodes 23 exceeds the breakdown voltage. Thereby, asustain discharge occurs and the first light emission occurs. With thisdischarge, the voltage of scan electrodes 22 starts to fall rapidly andthe voltage difference between scan electrodes 22 and sustain electrodes23 temporarily becomes lower than the breakdown voltage. Next, at thetime before approximately a half of the resonance period has elapsedsince time t1, switching element Q13 is turned on. Then, scan electrodes22 are coupled to power supply VS through switching element Q13, andthus clamped to voltage Vs at time t2.

(Period T2)

When scan electrodes 22 are clamped to voltage Vs in period T2 duringwhich the sustain pulse is maintained at voltage Vs as a predeterminedvoltage, the voltage difference between scan electrodes 22 and sustainelectrodes 23 in the discharge cells having undergone the addressdischarge in the address period exceeds the breakdown voltage again.Thereby, a sustaining discharge occurs and the second light emissionoccurs. In this manner, in the first sustain pulse state, at least twostrong light emissions are measured.

As described above, in the exemplary embodiment, a half of the period ofresonance between inductor L10 and interelectrode capacitance Cp is setto approximately 800 nsec. The rising time of the sustain pulse appliedto scan electrodes 22, i.e. period T1 from time t1 to time t2, is set toapproximately 650 nsec.

(Period T3)

In order to generate the first sustain pulse in period T3, switchingelement Q12 is turned on at time t3. Electric charge starts to move fromscan electrodes 22 to capacitor C10 through inductor L10, diode D12, andswitching element Q12, so that the voltage of scan electrodes 22 startsto fall. Because inductor L10 and interelectrode capacitance Cp form aresonance circuit, at the time when approximately a half of theresonance period has elapsed since time t3, the voltage of scanelectrodes 22 falls to the vicinity of 0 (V). Thereafter, switchingelement Q14 is turned on. Then, scan electrodes 22 are directly groundedthrough switching element Q14, and thus clamped to voltage 0 (V) at timet4. That is, period T3 is the falling time of the sustain pulse.

(Period T4)

Next, in order to generate the first sustain pulse in period T4, scanelectrodes 22 are kept clamped to 0 (V) from time t4. That is, period T4is a period during which the sustain pulse is maintained at 0 (V).

In this manner, in the first sustain pulse state, period T1, i.e. therising time of the sustain pulse, is approximately 650 nsec, which isset shorter than approximately 800 nsec, i.e. a half of the period ofresonance between inductor L10 and interelectrode capacitance Cp. Then,in the first sustain pulse state, two sustain discharges occur, and atleast two large light emissions are observed.

Next, the second sustain pulse state of FIG. 7 is described.

(Period T1)

In order to generate a sustain pulse in period T1, i.e. the rising timeof the sustain pulse, switching element Q11 is turned on at time t1.Then, electric charge starts to move from power recovery capacitor C10to scan electrodes 22 through switching element Q11, diode D11, andinductor L10, so that the voltage of scan electrodes 22 starts to rise.Because inductor L10 and interelectrode capacitance Cp form a resonancecircuit, at the time before a half of the resonance period has elapsedsince time t1, the voltage of scan electrodes 22 rises to the vicinityof Vs. At a first predetermined timing, i.e. time d1, data electrodedriving circuit 52 applies a data pulse to data electrodes 32. In thisexample, period Td1 from time t1 to time d1 is 550 nsec. Pulse width Tw1of the data pulse is 100 nsec, for example.

Applying the data pulse in this manner forces the voltage differencebetween scan electrodes 22 and sustain electrodes 23 in the dischargecells having undergone an address discharge in the address period toexceed the breakdown voltage. Thereby, the first sustain dischargestarts and the first light emission occurs. The light emission at thistime is influenced by the discharge caused by application of the datapulse, and is stronger than the first light emission of the firstsustain pulse. With this discharge, the voltage of scan electrodes 22starts to fall rapidly and the voltage difference between scanelectrodes 22 and sustain electrodes 23 temporarily becomes lower thanthe breakdown voltage. Thereafter, at the time before a half of theresonance period has elapsed since time t1, switching element Q13 isturned on. Then, scan electrodes 22 are coupled to power supply VSthrough switching element Q13, and thus clamped to voltage Vs at timet2.

In the exemplary embodiment, time d1 before scan electrodes 22 areclamped to voltage Vs is set to the first predetermined timing. However,similarly, time d1 before sustain electrodes 23 are clamped to voltageVs is also the first predetermined timing.

In this example, period Td1 from time t1 to time d1, i.e. the firstpredetermined timing, is set to 550 nsec. However, period Td1 is notnecessarily limited to this value, and varies with the design conditionsfor panel 10. In terms of reducing the phenomenon of persistence ofvision, and making the display luminance of each discharge cell uniform,an optimum value can be easily selected.

(Period T2)

When scan electrodes 22 are clamped to voltage Vs in period T2 duringwhich the sustain pulse is maintained at voltage Vs as the predeterminedvoltage, the second sustain discharge occurs and the second lightemission occurs in the discharge cells where the first sustain dischargehas started.

The operation in period T3 and period T4 is similar to that in the firstsustain pulse state, and the description of that operation is omitted.

In this manner, in the second sustain pulse state, the sustain pulse andthe data pulse cause two sustain discharges, and at least two largelight emissions are observed. However, the first light emission iscaused with the application of the data pulse, and thus the first lightemission is strong and the second light emission is relatively weakerthan the first light emission caused with the application of the datapulse. That is, data electrode driving circuit 52 of the exemplaryembodiment applies the data pulse to data electrodes 32 at the timingsuch that the light emission of the first discharge is stronger than thelight emission of the second discharge.

Next, the third sustain pulse state of FIG. 8 is described.

(Period T1)

In order to generate a sustain pulse in period T1, i.e. the rising timeof the sustain pulse, switching element Q11 is turned on at time t1.Then, electric charge starts to move from power recovery capacitor C10to scan electrodes 22 through switching element Q11, diode D11, andinductor L10, so that the voltage of scan electrodes 22 starts to rise.Because inductor L10 and interelectrode capacitance Cp form a resonancecircuit, at the time before a half of the resonance period has elapsedsince time t1, the voltage of scan electrodes 22 rises to the vicinityof Vs. Then, in the discharge cells having undergone an addressdischarge in the address period, the voltage difference between scanelectrodes 22 and sustain electrodes 23 exceeds the breakdown voltage.Thereby, a sustain discharge occurs and the first light emission occurs.With this discharge, the voltage of scan electrodes 22 starts to fallrapidly and the voltage difference between scan electrodes 22 andsustain electrodes 23 temporarily becomes lower than the breakdownvoltage. Thereafter, at the time before a half of the resonance periodelapses since time t1, switching element Q13 is turned on. Then, scanelectrodes 22 are coupled to power supply VS through switching elementQ13, and thus clamped to voltage Vs at time t2.

(Period T2)

When scan electrodes 22 are clamped to voltage Vs in period T2 duringwhich the sustain pulse is maintained at voltage Vs as the predeterminedvoltage, the second sustain discharge occurs and the second lightemission occurs in the discharge cells where the first sustain dischargehas started. Here, at a second predetermined timing after scanelectrodes 22 have been clamped to voltage Vs, i.e. time d2, dataelectrode driving circuit 52 applies a data pulse to data electrodes 32.In this example, period Td2 from time t1 to time d2 is 750 nsec. Pulsewidth Tw2 of the data pulse is 100 nsec, for example. With theapplication of the data pulse in this manner, the second light emissionis influenced by the discharge caused by the data pulse, and isrelatively stronger than the second discharge of the first sustainpulse. That is, data electrode driving circuit 52 of the exemplaryembodiment applies the data pulse to data electrodes 32 at the timingsuch that the light emission of the second discharge is stronger thanthe light emission of the first discharge.

In the exemplary embodiment, time d2 after scan electrodes 22 have beenclamped to voltage Vs is set to the second predetermined timing.However, similarly, time d2 after sustain electrodes 23 have beenclamped to voltage Vs is also the second predetermined timing.

As for the second predetermined timing, i.e. time d2, in this example,period Td2 from time t1 to time d2 is set to 750 nsec. However, periodTd2 is not necessarily limited to this value, and varies with the designconditions for panel 10. In terms of reducing the phenomenon ofpersistence of vision, and making the display luminance of eachdischarge cell uniform, an optimum value can be easily selected.

Again, the operation in period T3 and period T4 is similar to that inthe first sustain pulse state, and the description of that operation isomitted.

In this manner, in the third sustain pulse state, the sustain pulse andthe data pulse cause two sustain discharges, and at least two largelight emissions are observed. However, because the second light emissionis caused with the application of the data pulse, the second lightemission is strong, and the first light emission is relatively weakerthan the second light emission caused with the application of the datapulse.

As described above, in the exemplary embodiment, the timing at whichdata electrode driving circuit 52 applies the data pulses to dataelectrodes 32 is before or after the timing at which sustain pulsesapplied to scan electrodes 22 or sustain electrodes 23 are clamped tovoltage Vs as the predetermined voltage. In this manner, this operationcan reduce the phenomenon of persistence of vision itself and make thedisplay luminance of each discharge cell uniform.

In the examples of the exemplary embodiment, as shown in FIG. 9 and FIG.10, three states, i.e. the first sustain pulse state, the second sustainpulse state, and the third sustain pulse state, are switched andarranged. However, the exemplary embodiment is not limited to theseexamples. For example, scan electrodes 22, sustain electrodes 23, anddata electrodes 32 may be driven with pulses arranged in the followingorder: the first sustain pulse state; the third sustain pulse state; thethird sustain pulse state; the first sustain pulse state; the firstsustain pulse state; and the second sustain pulse state. In this manner,the arrangement order of the first sustain pulse state, the secondsustain pulse state, the third sustain pulse state is not limited to theabove combinations.

In the description of the exemplary embodiment, the pulses are generatedso that the three states, i.e. the first sustain pulse state, the secondsustain pulse state, and the third sustain pulse state, are switched.However, in the present invention, two types of pulse state, e.g. thefirst sustain pulse state and the second sustain pulse state, and thesecond sustain pulse state and the third sustain pulse state, may becombined and arranged. The present invention is not necessarily limitedto the combination of three types of state.

In the combination of two types of state as described above, it ispreferable to cause the two states with the same degree of probabilityin terms of reducing the phenomenon of persistence of vision itself andmaking the display luminance of each discharge cell uniform. Further,when pulses are generated so that the three states, i.e. the firstsustain pulse state, the second sustain pulse state, and the thirdsustain pulse state, are switched, it is preferable to cause the threestates with the same degree of probability also in terms of reducing thepower consumption.

In the description of the exemplary embodiment, one filed is dividedinto ten subfields (the first SF, and the second SF through the tenthsubfield), and the respective subfields have luminance weights of 1, 2,3, 6, 11, 18, 30, 44, 60 and 81. However, in the present invention, thenumber of subfields and the luminance weights of the respectivesubfields are not limited to the above values.

In the description of the exemplary embodiment, an all-cell initializingoperation is performed in the initializing period of the first SF, and aselective initializing operation is performed in the initializing periodof the second SF. However, the present invention is not limited to thisstructure, and the all-cell initializing operation or selectiveinitializing operation may be performed optionally in each subfield.

In the description of the exemplary embodiment, the same inductor isused for power supply and power recovery. However, the present inventionis not limited to this structure. A structure using different inductorsfor power supply and power recovery, e.g. a structure having separatepower supply path and power recovery path, may be used.

In the exemplary embodiment, the xenon partial pressure of the dischargegas is set to 10%. However, other xenon partial pressures may be used.In such a case, the driving voltage is set to a value appropriate forthe panel.

In the description of the exemplary embodiment, pulse width Tw1 andpulse width Tw2 of the data pulses to be applied to data electrodes 32in the second sustain pulse state and the third sustain pulse state areset to the same value of 100 nsec. However, these pulse widths may beset to different values. That is, pulse width Tw1 and pulse width Tw2 ofthe data pulses to be applied to data electrodes 32 by data electrodedriving circuit 52 may be different according to the timing from theapplication of the sustain pulse. Pulse width Tw1 may be set fromapproximately 50 nsec to 1000 sec, for example. Pulse width Tw2 may beset from 50 nsec to the time period until time t3, for example.

The specific values used in the exemplary embodiment are only examples.It is preferable to set values optimum for the characteristics of thepanel and the specifications of the plasma display device for each case.

INDUSTRIAL APPLICABILITY

The present invention is useful as a plasma display device and drivingmethod for a panel that provide high-fidelity image display with highimage display quality, reduce the phenomenon of persistence of visionitself, and consume less power.

REFERENCE SIGNS LIST

1 Plasma display device

10 Panel

21 Front plate

22 Scan electrode

23 Sustain electrode

24 Display electrode pair

25, 33 Dielectric layer

26 Protective layer

31 Rear plate

32 Data electrode

34 Barrier rib

35 Phosphor layer

51 Image signal processing circuit

52 Data electrode driving circuit

53 Scan electrode driving circuit

54 Sustain electrode driving circuit

55 Timing generating circuit

100, 200 Sustain pulse generating circuit

110, 210 Power recovery circuit

120, 220 Clamp circuit

Tw1 Pulse width

Tw2 Pulse width

1. A plasma display device comprising: a plasma display panel including:a first substrate having display electrode pairs in a paralleldirection, each of the display electrode pairs being formed of a scanelectrode and a sustain electrode; and a second substrate having dataelectrodes in a vertical direction, the first substrate and the secondsubstrate being disposed so that discharge cells are formed inintersecting parts of the display electrode pairs and the dataelectrodes; a scan electrode driving circuit for driving the scanelectrodes; a sustain electrode driving circuit for driving the sustainelectrodes; and a data electrode driving circuit for driving the dataelectrodes, the plasma display panel being driven by a subfield methodwhere one field is formed of a plurality of subfields, wherein, in asustain period of at least one of the subfields, the scan electrodedriving circuit and the sustain electrode driving circuit apply aplurality of sustain pulses alternately to the scan electrodes and thesustain electrodes, and the data electrode driving circuit applies adata pulse to the data electrodes by changing a timing according to thesustain pulses while the sustain pulses are applied.
 2. The plasmadisplay device of claim 1, wherein the data electrode driving circuitapplies the data pulse to the data electrodes at the timing such that alight emission of a first discharge is stronger than a light emission ofa second discharge.
 3. The plasma display device of claim 1, wherein thedata electrode driving circuit applies the data pulse to the dataelectrodes at the timing such that a light emission of a seconddischarge is stronger than a light emission of a first discharge.
 4. Theplasma display device of claim 1, wherein the timings at which the dataelectrode driving circuit applies the data pulse to the data electrodesare a first predetermined timing and a second predetermined timing. 5.The plasma display device of claim 1, wherein the timing at which thedata electrode driving circuit applies the data pulse to the dataelectrodes is before or after a timing at which the sustain pulsesapplied to the scan electrodes or the sustain electrodes are clamped toa predetermined voltage.
 6. A driving method for a plasma displaydevice, the plasma display device including: a plasma display panelincluding: a first substrate having display electrode pairs in aparallel direction, each of the display electrode pairs being formed ofa scan electrode and a sustain electrode; and a second substrate havingdata electrodes in a vertical direction, the first substrate and thesecond substrate being disposed so that discharge cells are formed inintersecting parts of the display electrode pairs and the dataelectrodes; a scan electrode driving circuit for driving the scanelectrodes; a sustain electrode driving circuit for driving the sustainelectrodes; and a data electrode driving circuit for driving the dataelectrodes, the plasma display panel being driven by a subfield methodwhere one field is formed of a plurality of subfields, the methodcomprising: in a sustain period of at least one of the subfields,applying sustain pulses alternately to the scan electrodes and thesustain electrodes using the scan electrode driving circuit and thesustain electrode driving circuit; and applying a data pulse to the dataelectrodes using the data electrode driving circuit by changing a timingwhile the sustain pulses are applied.